The invention relates to a retainer for retaining a cutting tool in a support block.
Cutting tool assemblies for such applications as mining or road milling typically comprise a cutting tool, sometimes referred to as a cutting pick, rotatably mounted within a support block. The support block in turn is mounted onto a drum or other body, typically by welding, which in turn is driven by a suitable drive means. When a number of such support blocks carrying cutting tools are mounted onto a drum, and the drum is driven, the cutting tools will engage and break up the material sought to be mined or removed. The general operation of such a mining or construction machine is well known in the art.
Various retainers have been proposed or used to mount a cutting tool, rotatably or otherwise, within a support block. For example, U.S. Pat. No. 4,505,058 to Peterson shows a retainer having two legs. This retainer is intended to be used with a support block having a recess with specially configured sidewalls which cooperate with the bends in the retainer legs to hold the retainer in place. More specifically, the sidewalls of the recess include projections to limit movement of the retainer with respect to the support block. This type of retainer is relatively difficult to move in order to disengage the retainer from the cutting tool in that a screwdriver or other similar object must be inserted into the recess and under the top of the retainer in order to pry and move the retainer. Like other similar retainers relying on prongs, the two legs of this retainer provide only four shear zones or areas where the retainer overlaps both the cutting tool and the support block. Because these shear zones prevent disengagement of the cutting tool from the support block, the number of such shear zones relates to the strength and durability of the retainer.
U.S. Pat. No. 4,883,129 to Lonn et al. shows another retainer which overlaps a cutting tool shank and a support block along substantially the entire length of the retainer. Consequently, the retainer provides a single, continuous shear zone along its entire length. However, this type of retainer is difficult to install and remove. More specifically, this retainer does not provide any slots or openings which may be grasped or which may receive a device for prying the retainer from the cutting tool shank. Furthermore, because the portion of the retainer that overlaps the support block is relatively narrow, this type of retainer does not sufficiently secure the cutting tool within the support block over an extended period of time.
The invention addresses the shortcomings of the prior art by providing an improved retainer that is adapted to engage a recess in a cutting tool for securing the cutting tool to a support block.
In one embodiment of the invention, the retainer includes a retainer body having a main portion with first and second ends. The main portion defines a continuous shear zone having first and second ends. The retainer body further includes a protruding portion disposed between the ends of the continuous shear zone and spaced away from the ends of the main portion. The protruding portion extends radially from the main portion and is adapted to overlap the support block when the retainer is engaging the recess.
The protruding portion preferably has an outer surface that is engageable with an installation/removal device for installing the retainer in the recess and for removing the retainer from the recess. Advantageously, with such a configuration, the retainer may be easily installed on and removed from the cutting tool.
The protruding portion is preferably a solid projection, such as a lobe, so that the protruding portion is a rigid extension of the retainer body. Alternatively, the protruding portion may have any suitable configuration.
Furthermore, the retainer body may include additional protruding portions. For example, the retainer body may include at least two or at least three protruding portions extending radially from the main portion. Such additional protruding portions may be used to improve contact between the retainer body and an installation/removal device.
Preferably, the continuous shear zone extends through an angle of at least one hundred eighty degrees. With such a configuration, the retainer has significant strength and durability characteristics.
The main portion may also form part of a helix. With such a configuration, movement of the cutting tool with respect to the support block can be reduced or eliminated.
In another embodiment of the invention, the retainer includes a retainer body having a main portion that defines a continuous shear zone, and at least three protruding portions extending radially from the main portion. Each protruding portion is adapted to overlap the support block when the retainer is engaging the recess.
In yet another embodiment of the invention, the retainer includes a retainer body having first and second ends, and a protruding portion disposed between the ends and spaced away from the ends. The protruding portion has a width and defines a continuous shear zone along the width.
Furthermore, the retainer described above may be provided with at least two additional protruding portions disposed between the ends of the retainer body. Preferably each additional protruding portion also defines a continuous shear zone. With such a configuration, strength and durability of the retainer is improved.
While an exemplary retainer is illustrated and disclosed, such disclosure should not be construed to limit the claims. It is anticipated that various modifications and alternative designs may be made without departing from the scope of the invention.